Calculator

Abstract

A calculator of flat design with a surface chart showing marginal scales and diagonal inner ones. The top of the calculator serves as a cover attached marginally to a case underneath. Also, the top has a diagonal slot, and is surmounted by a flat pointer which has a similar slot, and can be slid and rotated to relate to numerical values in the scales. An axial post is installed to pass through and be movable to any desired point in the slots, with means disengaging the post by finger pressure for movement away from said point.

I claim: 
     
       1. A calculator having a top, a surface chart on the latter marked with marginal and diagonal scales usable for nomographic calculations, said top containing a diagonal slot, a double-ended pointer above said chart having a longitudal centerline and a slot registering with said center line and the top slot when the pointer is rotated to match the diagonal direction of same, an axial post having a head passing through both slots and being slidable therein, the axial post having an enlargement underneath said top surface with a friction washer, and means bearing on the enlargement from underneath to hold said washer in engagement with the under surface of said top along its slot and check the axial post from lateral movement while maintaining said post head spaced above said chart, said pointer being slidable along said top slot and rotatable about said post to balance values in said scales in keeping with a desired numerical equation. 
     
     
       2. The structure of claim 1 wherein manual depression of said head lowers the enlargement and washer and frees the post for sliding movement in either or both of said slots. 
     
     
       3. The structure of claim 2 wherein said means bearing on the enlargement comprises a spring sheet on at least one side of the axial post and extending along the underside of said top.